Răspuns:
a) M H2O=2×1+16=18g/mol ,
18g H2O...........16g O
100G H2O..........xg O =>x=16×100/18=>x=88,88%O
b) M H2SO4=2+32+4×16=98g/mol
98g H2SO4................64g O
100g H2SO4.................x g O =>x=64×100/98=>x=65,3%O
C) MHNO3=1+14+3×16=63g/mol
63g HNO3...................48gO
100gHNO3................xgO
x=100×48/63=76,19%O
d) M(NH4)2CO3=2×14+8×1+12+3×16==96g/mol
96g(NH4)2CO3............ 48gO
100g(NH4)2CO3........xgO
x=100×48/96=50%
Explicație: